scholarly journals TROPOMI aerosol products: evaluation and observations of synoptic-scale carbonaceous aerosol plumes during 2018–2020

2020 ◽  
Vol 13 (12) ◽  
pp. 6789-6806
Author(s):  
Omar Torres ◽  
Hiren Jethva ◽  
Changwoo Ahn ◽  
Glen Jaross ◽  
Diego G. Loyola

Abstract. TROPOspheric Monitoring Instrument (TROPOMI) near-ultraviolet (near-UV) radiances are used as input to an inversion algorithm that simultaneously retrieves aerosol optical depth (AOD), single-scattering albedo (SSA), and the qualitative UV aerosol index (UVAI). We first present the TROPOMI aerosol algorithm (TropOMAER), an adaptation of the currently operational OMI near-UV (OMAERUV and OMACA) inversion schemes that takes advantage of TROPOMI's unprecedented fine spatial resolution at UV wavelengths and the availability of ancillary aerosol-related information to derive aerosol loading in cloud-free and above-cloud aerosols scenes. TROPOMI-retrieved AOD and SSA products are evaluated by direct comparison to sun-photometer measurements. A parallel evaluation analysis of OMAERUV and TropOMAER aerosol products is carried out to separately identify the effect of improved instrument capabilities and algorithm upgrades. Results show TropOMAER improved levels of agreement with respect to those obtained with the heritage coarser-resolution sensor. OMI and TROPOMI aerosol products are also intercompared at regional daily and monthly temporal scales, as well as globally at monthly and seasonal scales. We then use TropOMAER aerosol retrieval results to discuss the US Northwest and British Columbia 2018 wildfire season, the 2019 biomass burning season in the Amazon Basin, and the unprecedented January 2020 fire season in Australia that injected huge amounts of carbonaceous aerosols in the stratosphere.

2020 ◽  
Author(s):  
Omar Torres ◽  
Hiren Jethva ◽  
Changwoo Ahn ◽  
Glen Jaross ◽  
Diego G. Loyola

Abstract. TROPOMI near UV radiances are used as input to an inversion algorithm that simultaneously retrieves aerosol optical depth (AOD) and single scattering albedo (SSA) as well as the improved qualitative UV Aerosol Index (UVAI) that accurately accounts for the scattering effects of water clouds. We first present the TROPOMI aerosol algorithm (TropOMAER), an adaptation of the currently operational OMI near UV (OMAERUV & OMACA) inversion schemes, that take advantage of TROPOMI’s unprecedented fine near UV spatial resolution and the availability of ancillary aerosol-related information to derive aerosol loading in cloud-free and above-cloud aerosols scenes. An evaluation analysis of TROPOMI retrieved AOD/SSA products using sun-photometer observations shows improved levels of agreement with respect to those obtained with the heritage coarser resolution sensor. We then use TropOMAER aerosol retrieval results to discuss the the US Northwest and British Columbia 2018 wildfire season, the 2019 biomass burning season in the Amazon Basin, and the unprecedented January 2020 fire season in Australia that injected huge amounts of carbonaceous aerosols in the stratosphere.


2019 ◽  
Vol 12 (12) ◽  
pp. 6489-6503
Author(s):  
Hiren Jethva ◽  
Omar Torres

Abstract. The aerosol single-scattering albedo (SSA) retrieved by the near-UV algorithm applied to the Aura Ozone Monitoring Instrument (OMI) measurements (OMAERUV) is compared with an independent inversion product derived from the sky radiometer network SKYNET – a ground-based radiation observation network with sites in Asia and Europe. The present work continues previous efforts to evaluate the consistency between the retrieved SSA from satellite and ground sensors. The automated spectral measurements of direct downwelling solar flux and sky radiances made by the SKYNET Sun-sky radiometer are used as input to an inversion algorithm that derives spectral aerosol optical depth (AOD) and single-scattering albedo (SSA) in the near-UV to near-IR spectral range. The availability of SKYNET SSA measurements in the ultraviolet region of the spectrum allows, for the first time, a direct comparison with OMI SSA retrievals eliminating the need of extrapolating the satellite retrievals to the visible wavelengths as is the case in the evaluation against the Aerosol Robotic Network (AERONET). An analysis of the collocated retrievals from over 25 SKYNET sites reveals that about 61 % (84 %) of OMI–SKYNET matchups agree within the absolute difference of ±0.03 (±0.05) for carbonaceous aerosols, 50 % (72 %) for dust aerosols, and 45 % (75 %) for urban–industrial aerosol types. Regionally, the agreement between the two inversion products is robust over several sites in Japan influenced by carbonaceous and urban–industrial aerosols; at the biomass burning site Phimai in Thailand; and the polluted urban site in New Delhi, India. The collocated dataset yields fewer matchups identified as dust aerosols mostly over the site Dunhuang with more than half of the matchup points confined to within ±0.03 limits. Altogether, the OMI–SKYNET retrievals agree within ±0.03 when SKYNET AOD (388 or 400 nm) is larger than 0.5 and the OMI UV Aerosol Index is larger than 0.2. The remaining uncertainties in both inversion products can be attributed to specific assumptions made in the retrieval algorithms, i.e., the uncertain calibration constant, assumption of spectral surface albedo and particle shape, and subpixel cloud contamination. The assumption of fixed and spectrally neutral surface albedo (0.1) in the SKYNET inversion appears to be unrealistic, leading to underestimated SSA, especially under lower aerosol load conditions. At higher AOD values for carbonaceous and dust aerosols, however, retrieved SSA values by the two independent inversion methods are generally consistent in spite of the differences in retrieval approaches.


2021 ◽  
Vol 14 (6) ◽  
pp. 4053-4068
Author(s):  
Mengying Bao ◽  
Yan-Lin Zhang ◽  
Fang Cao ◽  
Yu-Chi Lin ◽  
Yuhang Wang ◽  
...  

Abstract. Carbonaceous aerosols have great influence on the air quality, human health and climate change. Except for organic carbon (OC) and elemental carbon (EC), brown carbon (BrC) mainly originates from biomass burning as a group of OC, with strong absorption from the visible to near-ultraviolet wavelengths, and makes a considerable contribution to global warming. Large numbers of studies have reported long-term observation of OC and EC concentrations throughout the world, but studies of BrC based on long-term observations are rather limited. In this study, we established a two-wavelength method (658 and 405 nm) applied in the Sunset thermal–optical carbon analyzer. Based on a 1-year observation, we firstly investigated the characteristics, meteorological impact and transport process of OC and EC. Since BrC absorbs light at 405 nm more effectively than 658 nm, we defined the enhanced concentrations (dEC = EC405 nm − EC658 nm) and gave the possibility of providing an indicator of BrC. The receptor model and MODIS fire information were used to identify the presence of BrC aerosols. Our results showed that the carbonaceous aerosol concentrations were the highest in winter and lowest in summer. Traffic emission was an important source of carbonaceous aerosols in Nanjing. Receptor model results showed that strong local emissions were found for OC and EC; however, dEC was significantly affected by regional or long-range transport. The dEC/OC and OC/EC ratios showed similar diurnal patterns, and the dEC/OC increased when the OC/EC ratios increased, indicating strong secondary sources or biomass burning contributions to dEC. A total of two biomass burning events both in summer and winter were analyzed, and the results showed that the dEC concentrations were obviously higher on biomass burning days; however, no similar levels of the OC and EC concentrations were found both in biomass burning days and normal days in summer, suggesting that biomass burning emissions made a great contribution to dEC, and the sources of OC and EC were more complicated. Large number of open fire counts from the northwestern and southwestern areas of the study site were observed in winter and significantly contributed to OC, EC and dEC. In addition, the nearby Yangtze River Delta area was one of the main potential source areas of dEC, suggesting that anthropogenic emissions could also be important sources of dEC. The results proved that dEC can be an indicator of BrC on biomass burning days. Our modified two-wavelength instrument provided more information than the traditional single-wavelength thermal–optical carbon analyzer and gave a new idea about the measurement of BrC; the application of dEC data needs to be further investigated.


2020 ◽  
Author(s):  
Karthik Venkatraman ◽  
Vijay Bhaskar ◽  
Amit Kesarkar

Abstract Fires provoke land degradation, deforestation, imbalance in the ecosystem, and promote changes in land use. To add more vein aerosols such as Black Carbon (BC) and Organic Carbon (OC) were emitted during the combustion event which plays a major role in climate change, pollution, and health. Hence this study aims to estimate the emission, residence, dry deposition flux, and sequestering ability of deposited BC and OC from different vegetative fires across India using MODIS satellite data from 2013 to 2019. It was observed that the mean OC and BC emission were about 5.08 × 107 tonnes 4.48 × 106 tonnes during the fire season across India. On a national scale, cropland fires contributed the largest portion (80%) of total carbonaceous aerosol emissions from open fires. In co-emission of species, forest shares a maximum relationship (> 92 percent) among carbonaceous aerosols. Estimation of deposition flux of emitted species showed cropland has higher deposition rates with a residence period ranging between 7hours to 23days. From the observed results, it is evident that higher aerosol emission combined with negligible deposition will be a potential threat to the environment. Waste utilization promoting strategies has to be adopted in India since agriculture contributes to major aerosols emission.


2019 ◽  
Author(s):  
Hiren Jethva ◽  
Omar Torres

Abstract. The aerosol single-scattering albedo (SSA) retrieved by the near-UV algorithm applied to the Aura/Ozone Monitoring Instrument (OMI) measurements (OMAERUV) is compared with an independent inversion product derived from the sky radiometer network SKYNET-a ground-based radiation observation network span over Asia and Europe. The present work continues our efforts to evaluate the consistency between the retrieved SSA from satellite and ground sensors. The automated spectral measurements of direct downwelling solar flux and sky radiances made by SKYNET Sun-sky radiometer are used as input to an inversion algorithm that derives spectral aerosol optical depth (AOD) and single-scattering albedo (SSA) in the near-UV to near-IR spectral range. The availability of SKYNET SSA measurements in the ultraviolet region of the spectrum allows, for the first time, a direct comparison with OMI SSA retrievals eliminating the need of extrapolating the satellite retrievals to the visible wavelengths as the case in the evaluation against the Aerosol Robotic Network (AERONET). An analysis of the collocated retrievals from over 25 SKYNET sites reveals that about 61 % (84 %) of OMI-SKYNET matchups agree within the absolute difference of ± 0.03 (± 0.05) for carbonaceous aerosols, 50 % (72 %) for dust aerosols, 45 % (75 %) for urban-industrial aerosol types. Regionally, the agreement between the two inversion products was robust over several sites in Japan influenced by carbonaceous and urban-industrial aerosols, at the biomass burning site Phimai in Thailand, and polluted urban site in New Delhi, India. The collocated dataset yields fewer matchups identified as dust aerosols mostly over the site Dunhuang with more than half of the matchup points confined to within ± 0.03 limits. Combinedly, the OMI-SKYNET retrievals agree mostly within ± 0.03 for the AOD (388 or 400 nm) larger than 0.5 and UV Aerosol Index larger than 0.2. The remaining uncertainties in both inversion products can be attributed to specific assumptions made in the retrieval algorithms, i.e., the uncertain calibration constant, assumption of spectral surface albedo and particle shape, and sub-pixel cloud contamination. The assumption of fixed and spectrally neutral surface albedo (0.1) in the SKYNET inversion appears to be unrealistic, leading to a large underestimation of retrieved SSA, especially for low aerosol load conditions. At large AOD values for carbonaceous and dust aerosols, however, retrieved SSA values by the two independent inversion methods are generally consistent in spite of the differences in retrieval approaches.


Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 257
Author(s):  
Jin Sang Jung ◽  
Ji Hwan Kang

To investigate the impact of burning postharvest crop residues in home stoves, PM2.5 samples (particulate matter with a diameter of <2.5 μm) were collected every 3 h at a rural site in Daejeon, Korea during the postharvest season in 2014. A high concentration of levoglucosan was observed with a peak value of 3.8 µg/m3 during the sampling period. The average mannosan/levoglucosan ratio (0.18) at the rural site during a severe BB episode (levoglucosan > 1 μg/m3) was similar to burnings of pepper stems (0.19) and bean stems (0.18) whereas the average OC/levoglucosan ratio (9.9) was similar to burning of pepper stems (10.0), implying that the severe BB episode was mainly attributed to burning of pepper stems. A very strong correlation was observed between levoglucosan and organic carbon (OC) (R2 = 0.81) during the entire sampling period, suggesting that the emission of organic aerosols at the rural site was strongly associated with the burning of crop residues in home stoves. The average mannosan/levoglucosan ratio (0.17 ± 0.06) in the rural area was similar to that in a nearby urban area in Daejeon (0.16 ± 0.04). It was concluded that crop residue burning in a home stove for space heating is one of the important sources of carbonaceous aerosols not only in a rural area but also in the urban area of Daejeon, Korea during the postharvest season.


2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Richard Toro Araya ◽  
Robert Flocchini ◽  
Rául G. E. Morales Segura ◽  
Manuel A. Leiva Guzmán

Measurements of carbonaceous aerosols in South American cities are limited, and most existing data are of short term and limited to only a few locations. For 6 years (2002–2007), concentrations of fine particulate matter and organic and elemental carbon were measured continuously in the capital of Chile. The contribution of carbonaceous aerosols to the primary and secondary fractions was estimated at three different sampling sites and in the warm and cool seasons. The results demonstrate that there are significant differences in the levels in both the cold (March to August) and warm (September to February) seasons at all sites studied. The percent contribution of total carbonaceous aerosol fine particulate matter was greater in the cool season (53 ± 41%) than in the warm season (44 ± 18%). On average, the secondary organic carbon in the city corresponded to 29% of the total organic carbon. In cold periods, this proportion may reach an average of 38%. A comparison of the results with the air quality standards for fine particulate matter indicates that the total carbonaceous fraction alone exceeds the World Health Organization standard (10 µg/m3) and the United States Environmental Protection Agency standard (15 µg/m3) for fine particulate matter.


2021 ◽  
Author(s):  
Omar Torres ◽  
Hiren Jethva ◽  
Changwoo Ahn ◽  
Glen Jaross ◽  
Diego Loyola

&lt;p&gt;The NASA-TROPOMI aerosol algorithm (TropOMAER), is an adaptation of the currently operational OMI near-UV (OMAERUV &amp; OMACA) inversion schemes, that take advantage of TROPOMI&amp;#8217;s unprecedented fine spatial resolution at UV wavelengths, and the availability of ancillary aerosol-related information to derive aerosol loading in cloud-free and above-cloud aerosols scenes. In this presentation we will introduce the NASA TROPOMI aerosol algorithm and discuss initial evaluation results of retrieved aerosol optical depth (AOD) and single scattering albedo (SSA) by direct comparison to AERONET AOD direct measurements and SSA inversions. We will also demonstrate TropOMAER retrieval capabilities in the context of recent continental scale aerosol events.&lt;/p&gt;


1996 ◽  
Vol 14 (1) ◽  
pp. 43-58 ◽  
Author(s):  
HAIYIN SUN ◽  
DUANE A. JACKSON ◽  
MURRAY CLARK ◽  
MALAY K. MAZUMDER

2019 ◽  
Author(s):  
Bruna A. Holanda ◽  
Mira L. Pöhlker ◽  
Jorge Saturno ◽  
Matthias Sörgel ◽  
Jeannine Ditas ◽  
...  

Abstract. Black carbon (BC) aerosols are influencing the Earth’s atmosphere and climate, but their microphysical properties, spatiotemporal distribution and long-range transport are not well constrained. This study analyzes the transatlantic transport of BC-rich African biomass burning (BB) pollution into the Amazon Basin, based on airborne observations of aerosol particles and trace gases in and off the Brazilian coast during the ACRIDICON-CHUVA campaign in September 2014, combining in-situ measurements on the research aircraft HALO with satellite remote-sensing and numerical model results. During flight AC19 over land and ocean at the Brazilian coastline in the northeast of the Amazon Basin, we observed a BC-rich atmospheric layer at ~ 3.5 km altitude with a vertical extension of ~ 0.3 km. Backward trajectory analyses suggest that fires in African grasslands, savannas, and shrublands were the main source of this pollution layer, and that the observed BB smoke had undergone more than 10 days of atmospheric transport and aging. The BC mass concentrations in the layer ranged from 0.5 to 2 μg m−3, and the BC particle number fraction of ~ 40 % was about 8 times higher than observed in a fresh Amazonian BB plume, representing the highest value ever observed in the region. Upon entering the Amazon Basin, the layer started to broaden and to subside, due to convective mixing and entrainment of the BB aerosol into the boundary layer. Satellite observations show that the transatlantic transport of pollution layers is a frequently occurring process, seasonally peaking in August/September. By analyzing the aircraft observations within the broader context of the long-term data from the Amazon Tall Tower Observatory (ATTO), we found that the transatlantic transport of African BB smoke layers has a strong impact on the north-central Amazonian aerosol population during the BB-influenced season (July to November). Specifically, the early BB season in this part of the Amazon appears to be dominated by African smoke, whereas the later BB season appears to be dominated by South American fires. This dichotomy is reflected in pronounced changes of aerosol optical properties such as the single scattering albedo (increasing from 0.85 in August to 0.90 in November) and the BC-to-CO enhancement ratio (decreasing from 7.4 to 4.4 ng m−3 ppb−1). Our results suggest that, despite the high amount of BC particles, the African BB aerosol act as efficient cloud condensation nuclei (CCN) with potentially important implications for aerosol-cloud interactions and the hydrological cycle in the Amazon Basin.


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